1. Field of the Invention
The present invention relates to patches for flexible materials and, more particularly, to a method and a patch repair system for repairing collapsible tanks and the like constructed of flexible materials.
2. Prior Art
The following patents were located which pertain to the invention.
U.S. Pat. No.IssuedInventorTitle4,874,445Oct. 17, 1989Patrick J.Method for RepairingLavoieFuel Tanks4,662,959May 5, 1987Howard F.Fiberglass GasolineMorganTank Repair Process5,281,288Jan. 25, 1994Thomas J.Tape for Affixing aMurray,Grip and Process foret al.Using Same5,091,239Feb. 25, 1992Richard A.Methods andPrzeworski,Adhesives for Bondinget al.Polyolefin Film6,582,759Jun. 24, 2003Zai-MingOptical ElementsQiu, et al.Comprising aFluorinated SurfaceTreatment ComprisingUrethane, Ester orPhosphate Linkages
Patrick Lavoie, in U.S. Pat. No. 4,874,445, discloses a method for repairing fuel tanks wherein after cleaning the surface of the tank a plastisol compound is spread over the damaged area and then heated. The method provides a fast and inexpensive procedure for repairing fuel tanks. The tanks are typically fabricated from steel and need repair because of rust and other corrosion.
In U.S. Pat. No. 4,662,959, Howard Morgan teaches a method for repairing gasoline tanks using a glass resin blend. His method is designed typically to repair fiberglass gasoline tanks.
The concept of using solvent activated adhesives is known in the art of adhesives, albeit not specifically to the repair of collapsible tanks and the like. A commonly employed application is the use of a solvent applied to a double-sided pressure sensitive tape to facilitate the installation of a grip onto a golf club. In U.S. Pat. No. 5,281,288, Tom Murray discloses in the background a method for using double-sided tape to mount the grip on the club. In the method the tape is wound around the end of the shaft and then coated with a solvent. The solvent improves the wetting capability of the adhesive and temporarily dissolves the adhesive enough so that it becomes slippery. While the adhesive is slippery the golf club grip can be slid onto the shaft. The solvent also helps the adhesive absorb the dust on the inside of the grip, and to bite into the interior walls of the rubber grip. Ultimately, the solvent is absorbed by the grip and evaporates leaving the adhesive to return to its former state, where it had a relatively high shear.
Another example of using solvent activated adhesives is provided in U.S. Pat. No. 5,091,239 by Przeworski. In the last line of column 1, Przeworski introduces the phrase “solvent activated adhesive,” where a solvent activated adhesive is one that is not sticky until plasticizing by the addition of solvent. This process of plasticizing the adhesive is known as solvent activation of dry adhesives. In column 2, line 30 he describes how a solvent is activated. “The solvent activated dry adhesive is preferably a thermoplastic, hard urethane with or without suitable additives.” In column 3, beginning on line 28 Przeworski goes on to say that the dry adhesive may comprise a single polyurethane or a mixture of one or more polyurethanes having an additive such as isocyanate. The dry adhesive as disclosed in this invention is coated on an olefinic film such as MOPP and BOPP. MOPP, and BOPP are oriented polypropylene films, not polyurethane thermoplastics. Other potential additives cited by Przeworski that can be added to the polyurethane adhesive include aziridine and/or a prepolymer made from di and trifunctional diols admixed with isocyanate. In column 4, lines 13-18, typical activating solvents mentioned include toluene, methyl ethyl ketone, ethyl acetate, methylene chloride, acetone, and tetrahydrofuran for TPU. Thermoplastic elastomer Kraton® is activated with hexane, cyclohexane, pentane and isopentane. Krayton is a trade name for Shell Chemicals' block copolymers, which usually have styrenic end-blocks and a butadienic or isoprenic polymeric mid-block.
In U.S. Pat. No. 6,582,759, Zai-Ming et al disclose optical elements which, in column 17, lines 64 and 65 utilize a solvent activated adhesive that can employ a uretdione. Examples are cited in column 20, lines 7 and 8. The art is very removed from tank repair, but this patent does utilize both a solvent activated adhesive, a urethane and an internally blocked isocyanate (uretdione).